This invention relates to a process for incorporating a hologram into a laminar structure with a photograph, and to a laminar structure so produced.
Laminar structures in the form of identification cards or badges which carry a photograph or other personalized information pertaining to the bearer are commonplace and have many recognized security and identification applications. Identification cards or badges, which may be worn on the person or carried by the card bearer, are disclosed, for example, in U.S. Pat. No. 2,361,670 (issued Oct. 31, 1944 to N. Whitehead); in U.S. Pat. No. 3,313,052 (issued Apr. 11, 1967 to R. L. Malster); and in U.S. Pat. No. 4,305,215 (issued Dec. 15, 1981 to S. C. Smith).
Such identification cards are often produced by laminating a photograph of the person authorized to use the identity card between two sheets of plastic or similar material. For example, U.S. Pat. No. 4,322,461, issued Mar. 30, 1982, describes an identity card structure and a method for the preparation thereof using a transferred adhesive. The laminar structures comprise a color diffusion transfer photographic print bonded to a vinyl sheet using an adhesive mixture of a vinyl acetate-ethylene copolymer and a hydroxylated polymer, and are prepared using an adhesive-supporting carrier sheet.
U.S. Pat. No. 4,101,701, issued July 18, 1978, describes an identity or credit card and a laminar assembly for preparing same. A layer comprising specific ethylene copolymers or mixtures thereof and a layer comprising a hydroxylated polymer is stated to be an especially effective heat-activateable adhesive in such cards.
U.S. Pat. No. 3,647,442, issued Mar. 7, 1972, describes a laminar structure comprising a diffusion transfer color photographic image on a stratum comprising a mixture of polyvinyl pyridine and polyvinyl alcohol, the surface of the stratum being bonded to the surface of a transparent layer of sheet material, and an identification card including such a laminar structure. into the card while wet (see column 3, lines 1-15).
U.S. Pat. No. 3,644,116, issued Feb. 22, 1972, describes a laminar structure comprising a photographic image in silver laminated to a transparent layer through or via a layer comprising a water-activated plasticized vinyl acetate polymer. The water-activated polymer is coated on the transparent layer, which is then dried. The photograph can be laminated wet (see column 4, line 65 to column 5, line 26).
(The term "wet" is used in the two preceding patents and in the present application to refer to a photograph which has just been developed and which thus has a high moisture content. When the photograph is produced using a diffusion transfer photographic process such as that described in U.S. Pat. No. 2,983,606, the wet photograph may also bear on its surface the residue of the processing composition used to develop the diffusion transfer photograph.)
U.S Pat. No. 3,582,439, issued June 1, 1971, and U.S. Pat. No. 3,614,839, issued Oct. 26, 1971, describe an identity card in which a laminar structure comprises a color photograph bonded to a sheet of vinyl through an ethylene-vinyl acetate copolymer tie coat.
U.S. Pat. No. 3,581,417, issued June 1, 1971, describes a novel product intended for use in, inter alia, an identity card, this product comprising an adhesive coated polyester film laminated to a cellulose ester through a tie-coat consisting essentially of plasticized nitrocellulose.
Attempts have also been made to incorporate holograms into identity cards and similar laminar structures, since holograms are inherently difficult to reproduce and thus render more difficult the counterfeiting of, or tampering with, the identity card. For example, U.S. Pat. No. 4,684,795, issued Aug. 4, 1987, describes an identification card and method of manufacturing the same in which a holographic image is embossed on a clear polyester carrier which is then coated with ferrous oxide to form a magnetic strip with an optically viewable holographic image thereon. The strip is then mounted on a plastic substrate, and the carrier discarded.
U.S. Pat. No. 4,597,814, issued July 1, 1986, describes a method of manufacturing an identification card whereby information is printed on a sheet of plastic material. A raised pattern is formed on a different sheet of material to create a holographic image. The resultant raised pattern sheet is attached to the surface of the sheet of plastic material by pressure sensitive adhesive. The surface of the plastic material is overlaminated with a transparent layer to form a sandwich, and heat and pressure are applied to fuse the overlaminated layers. The pattern sheet has a high melting point so that the image is viewed as three-dimensional through an overlaminated layer.
U.S Pat. No. 4,573,711, issued Mar. 4, 1986, describes a method of manufacturing a credit card including the fabrication of a plurality of plastic credit cards, as in sheet form, and then severing such cards into individual personal cards with coded information thereon for identifying the person or account to which the cards relate. Printed on such card is indicia indicating the card is "void". Fabricated separately from the respective cards are strips of hologram material which are sized to act as covers for overlying the "void" indicia and which incorporate optical images which may be characteristic of a particular account or institution to indicate the card is currently active. The indicia covers are stored separate from the cards and are only applied thereto as a last step prior to shipment of the cards from the place of storage to the customer. Consequently, any unauthorized person who gains possession of the cards without the accompanying hologram covers will find the cards ineffective for making unauthorized transactions relating to the accounts identified by such cards.
In commercial systems, it is highly desirable that an identity card or similar laminar structure be capable of being assembled using a wet photograph. Commercial "instant" or "on-the-spot" identity card issuance systems are typically employed to provide an identity card for immediate use. Such systems are typically based on color photographs from diffusion transfer photographic film units. Thus, the intended bearer of an identity card will report to an identity card issuance station where appropriate photographic materials and equipment are assembled. A data card containing personalized information relating to the bearer is prepared, usually by adding such information to a preprinted data card bearing information pertaining to the card issuing authority or association. The data card and the bearer are photographed simultaneously with a camera unit employing diffusion transfer photographic film, the film immediately developed and the identity card handed to its bearer. Such a system minimizes the time required of the bearer and the technician operating the equipment, and provides the maximum security since both the bearer and the technician can check that the card has been properly prepared. If the system cannot incorporate a wet photograph into the identity card, the preparation of the card must be delayed until the photograph has dried (with consequent increased loss of time of the bearer and the technician), or the apparatus used to prepare the card must incorporate a drying section for rapidly drying the photograph so that it can be incorporated into the identity card. The provision of such a drying section increases the complexity and cost of the apparatus used to prepare the card.
However, there are two problems which one must overcome to produce a secure laminar structure containing a wet photograph, a hologram and two sheets of material between which the photograph and the hologram are sandwiched. If one attempts to bond a hologram to a wet photograph, the water absorbed from the photograph will destroy the image of the hologram. In addition, if the hologram bonds to one of the sheets more strongly than it bonds to the photograph, it might be possible for a counterfeiter or tamperer to separate the photograph from the hologram, leaving the hologram attached to one of the sheets, and substitute a different photograph, thereby producing an apparently-authentic laminar structure with the proper hologram displayed.
Accordingly, there is a need for a process which permits a hologram to be incorporated into a laminar structure together with a wet photograph in such a manner that it is not possible to separate the hologram from the photograph and leave the hologram intact and attached to the sheets forming the outer surfaces of the laminar structure, and this invention provides such a process.